Transparent photocatalyst coating and methods of manufacturing the same

ABSTRACT

Methods for making photocatalyst compositions and elements exhibiting desired photocatalytic activity levels and transparency.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national phase of PCT/US2014/045413 filed on Jul.3, 2014 which claims priority to U.S. Application No. 61/843,266 filedon Jul. 5, 2013, the entire disclosures of which are incorporated byreference.

BACKGROUND

Visible-light activated photocatalysts can be deployed forself-cleaning, air, and water purification and many other interestingapplications usually without any post-deployment non-renewable energycosts. This is because the photocatalysts are able to decomposepollutants (like dyes, volatile organic compounds, and NO_(x)) usingavailable ambient light like solar radiation or indoor and outdoorlighting. With the anticipated rapid adoption of UV-free indoor lighting(like LEDs and OLEDs), it is important to find ways to deployvisible-light activated photocatalysts in indoor applications forinstance in cleaning room air in domestic, public, and commercial spacesespecially in confined spaces like aircraft, public buildings, etc.Moreover, additional applications for antibacterial surfaces andself-cleaning materials can have wide applicability in the food service,transportation, health care, and hospitality sectors.

Generally, photocatalytic coatings exhibit low photocatalytic activity,primarily due to low inherent activity of the base photocatalystmaterial as well as their incompatibility with the commonly usedbinders. Thus, there is a need for photocatalytic coatings and/or layersthat exhibit desired photocatalytic levels and transparency.

SUMMARY

Photocatalytic compositions that include a photocatalyst, anon-photocatalyst, and/or a co-catalyst may be useful for a variety ofphotocatalytic applications. Additionally, a co-catalyst may improve thephotocatalytic activity of a photocatalyst so that combination of aphotocatalyst and a co-catalyst is more active than a photocatalystalone. Furthermore, incorporation of photocatalytic materialco-catalysts into photocatalytic coatings may help to improve thetransparency and photocatalytic activity of the coating material.

Some embodiments include a method of manufacturing a coated articlecomprising: forming a thin layer of a photocatalytic composition bysputtering at least one photocatalytic source and at least onenon-photocatalytic source onto a target material in a sputtering gasatmosphere.

Some embodiments include a coated article obtainable by a methoddescribed herein.

Some embodiments include a photocatalytic material comprising: aphotocatalytic layer comprising tin and a non-photocatalytic materialcomprising copper, wherein part of the non-photocatalytic material is indirect contact with the photocatalytic layer. For some photocatalyticmaterials the photocatalytic layer and the non-photocatalytic materialhave a volume ratio that is about 1 to about 100 or about 3 to about 50.

In some embodiments, the photocatalyst can be Ti-based. In someembodiments, the photocatalyst can be responsive to visible light. Insome embodiments, the photocatalyst can be titanium dioxide, a dopedtitanium oxide, or a composite titanium oxide material powder.

In some embodiments, the photocatalyst can be W-based. In someembodiments, the photocatalyst can be responsive to visible light. Insome embodiments, the photocatalyst can be tungsten oxide, a dopedtungsten oxide powder, or a tungsten oxide composite material powder.

In some embodiments, the photocatalyst can be Sn-based. In someembodiments, the photocatalyst can be responsive to visible light. Insome embodiments, the photocatalyst can be tin oxide, a doped tin oxidepowder, or a tin oxide composite material powder.

In some embodiments, the photocatalyst can any combination or mixture ofSn-based, W-based, and/or Ti based materials. In some embodiments, thephotocatalyst can be responsive to visible light. In some embodiments,the photocatalyst can be a combination of at least one tin oxide, adoped tin oxide powder, or a tin oxide composite material powder. Insome embodiments, the photocatalyst can be a combination of at least onetin oxide, a doped tin oxide powder or a tin oxide composite materialpowder and at least one of titanium dioxide, a doped titanium oxide, ora composite titanium oxide material powder. In some embodiments, thephotocatalyst can be a combination of at least one tin oxide, a dopedtin oxide powder or a tin oxide composite material powder, and at leastone tungsten oxide, a doped tungsten oxide powder, or a tungsten oxidecomposite material powder. In some embodiments, the photocatalyst can bea combination of at least one of a tungsten oxide, a doped tungstenoxide powder, or a tungsten oxide composite material powder and at leastone of titanium dioxide, a doped titanium oxide, or a composite titaniumoxide material powder.

Some embodiments include a photocatalytic layer including theaforementioned photocatalytic composition. Some embodiments can furtherinclude a substrate, at least a portion of the photocatalytic materialcontacting the substrate.

Some embodiments include a transparent photocatalytic compositionincluding at least one photocatalyst material and at least one metaland/or co-catalyst. In some embodiments, the photocatalyst material andthe co-catalyst have refractive indices within about 0.75 of each other.

Some embodiments include a method of making a photocatalytic layerincluding forming the aforementioned compositions and applying thecompositions to a substrate.

In some embodiments, a method of manufacturing a coated article isprovided, the method comprising forming a thin layer of thephotocatalytic composition on a substrate by sputtering at least onephotocatalytic source and at least one non-photocatalytic source astarget material in a sputtering gas atmosphere. In some embodiments, thethin layer is substantially uniform across the substrate surface. Insome embodiments, the thin layer is substantially continuous across thesubstrate surface. In some embodiments, the at least one photocatalyticsource and the at least one non-photocatalytic source are intimatelycombined in the resulting thin layer. In some embodiments, the molarratio of photocatalyst to non-photocatalyst or metal is about 1:1 [50%to 50%]. In some embodiments, the molar ratio of photocatalyst tonon-photocatalyst or metal can be about 4:1 [80% to 20%]. In someembodiments, the photocatalytic source comprises at least one tinsource. In some embodiments, the at least one tin source is selectedfrom SnO₂ and Sn metal. In some embodiments, the photocatalytic sourcecomprises a tungsten source. In some embodiments, the tungsten sourcecan be selected from WO₃ and W metal. In some embodiments, thenon-photocatalytic source can comprise a metal. In some embodiments, themetal can be copper. In some embodiments, the photocatalyst is a tinoxide and the metal is copper. In some embodiments, the thin layer cancomprise a first layer formed from the at least one tin source and asecond layer formed from the at least one metal source. In someembodiments, at least one of or both the first layer and the secondlayer are substantially uniform and/or continuous across the substratesurface. In some embodiments, at least a portion of the first layer isin direct contact with at least a portion of the second layer. In someembodiments, substantially no layers or materials are located betweenthe first and second layers. In some embodiments, the thin layer cancomprise a co-sputtered layer formed from at least one tin source andthe at least one metal source. In some embodiments, the co-sputteredlayer is substantially uniform and/or continuous across the substratesurface. In some embodiments, the at least one tin source and the atleast one metal source in the co-sputtered layer are intimately combinedin the resulting co-sputtered layer. In some embodiments, the at leastone non-photocatalytic source can comprise a co-catalytic source. Insome embodiments, the at least one co-catalytic source can comprise CeO₂and/or In₂O₃. In some embodiments, the sputtering gas atmosphere cancomprise an inert gas. In some embodiments, the inert gas can be argon.In some embodiments, the sputtering gas atmosphere can comprise oxygen.In some embodiments, the thin layer can comprise a first layer formedfrom the at least one tungsten source and a second layer formed from theat least one co-catalyst source. In some embodiments, the thin layer cancomprise a co-sputtered layer formed from at least one tungsten sourceand the at least one co-catalyst source. In some embodiments, the molarratio of photocatalyst to CeO₂ is about 1:1 [50% to 50%]. In someembodiments, the molar ratio of photocatalyst to CeO₂ can be about 4:1[80% to 20%]. In some embodiments, the substrate can be heated at atemperature between room temperature and 500° C. In some embodiments,the substrate can be heated for a time between about 10 seconds andabout 2 hours. In some embodiments, a method of purifying air or wateris provided, the method comprising exposing the air or water to light inthe presence of a photocatalytic composition described herein. In someembodiments, the photocatalytic composition can remove greater thanabout 50% of the pollution in the air or water.

Some embodiments include a method of manufacturing a coated articleincluding forming a thin layer of the photocatalytic composition on asubstrate by sputtering at least one photocatalytic source and at leastone metal or co-catalytic source as target material in a sputtering gasatmosphere. In some embodiments, the photocatalytic source is SnO₂and/or tin (Sn) metal, WO₃ and/or tungsten (W) metal, and/or TiO₂ and/ortitanium metal. In some embodiments, the metal source is Cu. In someembodiments, the co-catalytic source is CeO₂.

Some embodiments include a method for making a photocatalytic layerincluding creating a dispersion comprising a photocatalyst, CeO₂, and adispersing media wherein the respective photocatalyst and CeO₂refractive indices are within 0.75 of each other, the molar ratio of thephotocatalyst to CeO₂ being between 1-99 molar % photocatalyst and 99-1molar % CeO₂, wherein the dispersion has about 2-50 wt % solidmaterials. The dispersion is applied to a substrate and heated at asufficient temperature and for a length of time to evaporatesubstantially all the dispersing media from the dispersion.

Some embodiments include a method of purifying air or water, the methodcomprising exposing the air or water to light in the presence of aphotocatalytic composition described herein.

Some embodiments include a method of removing a pollutant, comprisingexposing a material comprising the pollutant to light in the presence ofa photocatalytic composition described herein.

These and other embodiments are described in more detail herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic depiction of an embodiment of a photocatalyticcoating.

FIG. 2 is a schematic depiction of an embodiment of a photocatalyticcoated surface.

FIG. 3 is a schematic depiction of a sputtering apparatus formanufacturing a photocatalytic coated surface.

FIG. 4 is a schematic depiction of an embodiment of a photocatalyticcoated surface.

FIG. 5 is a schematic depiction of an embodiment of a photocatalyticcoated surface.

FIG. 6 is a schematic depiction of an embodiment of a photocatalyticcoated surface.

FIG. 7 is a graph depicting the antibacterial activity of an embodimentdescribed herein.

DETAILED DESCRIPTION

A photocatalyst includes any material that can activate or change therate of a chemical reaction as a result of exposure to light, such asultraviolet or visible light. In some embodiments, photocatalystmaterial may be an inorganic solid, such as a solid inorganicsemiconductor, that absorbs ultraviolet or visible light. For somematerials, photocatalysis may be due to reactive species (able toperform reduction and oxidation) being formed on the surface of thephotocatalyst from the electron-hole pairs generated in the bulk of thephotocatalyst by the absorption of electromagnetic radiation. In someembodiments, the photocatalyst has a conduction band with an energy ofabout 1 eV to about 0 eV, about 0 eV to about −1 eV, or about −1 eV toabout −2 eV, as compared to the normal hydrogen electrode. Somephotocatalysts may have a valence band with energy of about 3 eV toabout 3.5 eV, about 2.5 eV to about 3 eV, or about 2 eV to about 3.5 eV,or about 3.5 eV to about 5.0 eV as compared to the normal hydrogenelectrode.

Traditionally, photocatalysts could be activated only by light in the UVregime—i.e., wavelengths less than 380 nm. This is because of the widebandgap (>3 eV) of most semiconductors. However, in recent years byappropriately selecting materials or modifying existing photocatalysts,visible light photocatalysts have been synthesized (Asahi et al.,Science, 293: 269-271, 2001 and Abe et al., Journal of the AmericanChemical Society, 130(25): 7780-7781, 2008). A visible lightphotocatalyst includes a photocatalyst that is activated by visiblelight, e.g. light that is normally visible to the unaided human eye,such as at least about 380 nm in wavelength. Visible lightphotocatalysts can also be activated by UV light below 380 nm inwavelengths in addition to visible wavelengths. Some visible lightphotocatalyst may have a band gap that corresponds to light in thevisible range, such as a band gap greater than about 1.5 eV, less thanabout 3.5 eV, about 1.5 eV to about 3.5 eV, about 1.7 eV to about 3.3eV, or 1.77 eV to 3.27 eV.

Some photocatalysts may have a band gap of about 1.2 eV to about 6.2 eV,about 1.2 eV to about 1.5 eV, or about 3.5 eV to about 6.2 eV.

Some photocatalysts include oxide semiconductors such as TiO₂, ZnO, WO₃,SnO₂, In₂O₃, etc., and modifications thereof. Contemplated modificationsinclude doping and/or loading. Other materials, like complex oxides(SrTiO₃, BiVO₄) and some sulfides (CdS, ZnS), nitrides (GaN) and someoxynitrides (e.g. ZnO:GaN), may also display photocatalytic properties.Photocatalysts can be synthesized by those skilled in the art by avariety of methods including solid state reaction, combustion,solvothermal synthesis, flame pyrolysis, plasma synthesis, chemicalvapor deposition, physical vapor deposition, ball milling, and highenergy grinding.

In some embodiments, the photocatalyst can be an oxide semiconductor. Insome embodiments, the photocatalyst can be a titanium (Ti) compound. Insome embodiments, the photocatalyst can be a tungsten (W) compound. Insome embodiments, the respective Ti or W compounds can be a respectiveoxide, oxycarbide, oxynitride, oxyhalide, halide, salt, doped or loadedcompound. In some embodiments, the respective Ti or W compounds can beTiO₂, WO₃, or Ti(O,C,N)₂:Sn, such as Ti(O,C,N)₂:Sn wherein the molarratio of Ti:Sn is about 90:10 to about 80:20, or about 87:13. In someembodiments, the respective Ti or W compounds can be nanopowders,nanoparticles, and or layers comprising the same. In some embodiments,the photocatalyst may include ZnO, ZrO₂, SnO₂, CeO₂, SrTiO₃, BaTiO₃,In₂O₃, Cu_(x)O, Fe₂O₃, ZnS, Bi₂O₃, or BiVO₄.

Any useful amount of photocatalyst may be used. In some embodiments, thephotocatalyst material is at least about 0.01 molar % and less than 100molar % of the composition. In some embodiments, the photocatalystmaterial is about 20 molar % to about 80 molar %, about 30 molar % toabout 70 molar %, about 40 molar % to about 60 molar %, or about 50molar % of the composition.

SnO₂, TiO₂, and WO₃ compounds, e.g., nanopowders, can be prepared bymany different methods including thermal plasma (direct current andincluding radio frequency inductively-coupled plasma (RF-ICP)),solvothermal, solid state reaction, pyrolysis (spray and flame), andcombustion. Radio frequency inductively-coupled plasma (e.g. thermal)methods as described in U.S. Pat. No. 8,003,563, which is incorporatedherein in its entirety by reference, may be useful because of lowcontamination (no electrodes) and high production rates and facileapplication of precursors either in the gas, liquid, or solid form.Hence, radio frequency inductively-coupled plasma processes may bepreferred. For example, when preparing WO₃ nanopowders, a liquiddispersion of ammonium metatungstate in water (5-20 wt % solid in water)can be sprayed into the plasma volume using a two-fluid atomizer.Preferably, the precursor can be present to about 20 wt % solid inwater. The plasma can be operated at about 25 kW plate power with argon,nitrogen and/or oxygen gases. The particles formed from the condensedvapor from the plasma can then be collected on filters. In someembodiments, the particle surface areas range as measured using BET fromabout 1 m²/g to about 500 m²/g, about 15 m²/g to 30 m²/g, or about 20m²/g. In some embodiments, the obtained WO₃ may be heated from about200° C. to about 700° C. or about 300° C. to about 500° C.

In some embodiments, a photocatalyst can be doped with at least onenaturally occurring element, e.g. non-noble gas elements. Doped elementscan be provided as precursors added generally during synthesis. Dopedelements can be elements that are incorporated into the crystal latticeof the Ti or W compound, for example, as substituted within definedpositions within the crystal lattice or otherwise interstitiallyincluded within the crystal. In some embodiments, the dopant can beselected from one or more elements including alkali metals including Li,Na, K, Cs; alkali earth metals including Mg, Ca, Sr, Ba; transitionmetals including Fe, Cu, Zn, V, Ti (for W-based compounds), W (forTi-based compounds), Mo, Zr, Nb, Cr, Co, and Ni; lanthanide and actinidemetals; halogens; Group III elements (from the Dmitri Mendeleev/LotharMeyer style modern periodic table with elements arranged according toincreasing atomic number) including B, Al, Ga, In and TI, Group IVelements including Ca, Si, Ge, Sn; Group V elements including N, P, Bi;and Group VI elements including S and Se. For example, Indium Tin Oxide(ITO) can be considered SnO₂ doped with In₂O₃. In some embodiments, thephotocatalyst can be doped with at least one element selected from C, N,S, F, Sn, Zn, Mn, Al, Se, Nb, Ni, Zr, Ce, and Fe. In some embodiments,the photocatalyst may be self-doped, e.g., Ti³⁺ in place of Ti⁴⁺ in aTiO₂ matrix. Details of suitably doped photocatalytic materials arepresented in the U.S. Provisional Application No. 61/587,889, which ishereby incorporated by reference in its entirety.

In some embodiments, the photocatalytic material comprises one or moreof n-type UV photocatalytic material, n-type visible lightphotocatalytic material, p-type UV photocatalytic material, and/orp-type visible photocatalytic material. In some embodiments, the n-typevisible band gap semiconductors can optionally be WO₃, Ti(O,C,N)₂:Sn, orCeO₂. In some embodiments, the n-type UV photocatalytic material canoptionally be CeO₂, TiO₂, SnO₂, SrTiO₃, ATaO₃, ANbO₃ etc.; A=alkalimetal ion, such as A can Ca, Ba, and/or Sr. In some embodiments, p-typevisible band gap semiconductors can optionally be SiC, CuMO₂, M=Al, Cr.In some embodiments, the p-type UV photocatalytic material canoptionally be ZnIrO₂, ZnRhO₂, CuO, NiO, Mn₂O₃, Co₃O₄, and/or Fe₂O₃.

In some embodiments, the photocatalyst can be coated and/or loaded withat least one non-photocatalytic material. In some embodiments, thephotocatalyst can be coated and/or loaded with at least one metal.Coated and/or loaded elements can be provided by post synthesismethodologies like impregnation (Liu, M., Qiu, X., Miyauchi, M., andHashimoto, K., Cu(II) Oxide Amorphous NanoClusters Grafted Ti³⁺Self-Doped TiO₂: An Efficient Visible Light Photocatalyst. Chemistry ofMaterials, published online 2011), photoreduction (Abe et al., Journalof the American Chemical Society, 130(25): 7780-7781, 2008), and/orsputtering. In some embodiments, loading metals on photocatalysts may becarried out as described in U.S. Patent Publication Number 2008/0241542,which is incorporated herein in its entirety by reference. In someembodiments, the coated and/or loaded element is selected from nobleelements. In some embodiments, the loaded element can be selected fromat least one noble metal element, oxide, and/or hydroxide. In someembodiments, the noble metal elements include Au, Ag, Pt, Pd, Ir, Ru,Rh, or their oxides and/or hydroxides. In some embodiments, the coatedand/or loaded element is selected from transition metals, their oxidesand/or hydroxides. In some embodiments, the coated and/or loaded elementis selected from Fe and Cu and Ni or their oxide and hydroxides. In someembodiments, the coated and/or loaded element is chosen from differentgroups of elements including at least one transition metal and at leastone noble metal or their respective oxides and hydroxides.

According to some embodiments where a non-photocatalytic source materialis included with a photocatalytic composition—whether as a layerseparate from a layer comprising the photocatalytic composition,co-sputtered with the photocatalytic material, etc.—thenon-photocatalytic source material contains substantially no titanium.And where the non-photocatalytic material comprises a separate layer,the separate layer contains substantially no titanium.

In some embodiments, the thin layer is substantially uniform across thesubstrate surface. In some embodiments, the thin layer is substantiallycontinuous across the substrate surface. In some embodiments, the atleast one photocatalytic source and the at least one non-photocatalyticsource are intimately combined in the resulting thin layer. In someembodiments, at least one of or both the first layer and the secondlayer is substantially uniform and/or continuous across the substratesurface. In some embodiments, at least a portion of the first layer isin direct contact with at least a portion of the second layer. In someembodiments, no layers are located between the first and second layers.In some embodiments, the thin layer can comprise a co-sputtered layerformed from at least one tin source and the at least one metal source,such as copper. In some embodiments, the co-sputtered layer issubstantially uniform and/or continuous across the substrate surface. Insome embodiments, the at least one tin source and the at least one metalsource in the co-sputtered layer are intimately combined in theresulting co-sputtered layer.

These co-sputtering methods may be used to prepare a photocatalyticmaterial comprising a photocatalytic layer and a non-photocatalyticmaterial, wherein part of the non-photocatalytic material is in directcontact with the photocatalytic material.

For example, the photocatalytic material may be in the form of a thinlayer comprising a substantially continuous first layer formed from bysputtering a photocatalytic source and a second layer formed bysputtering a non-photocatalytic source. The second layer may be acontinuous layer, or may be composed of particles or islands dispersedover the surface of the continuous first layer. The photocatalyticmaterial may also comprise the non-photocatalytic material partially orcompletely embedded in the photocatalytic layer.

The first layer, or the photocatalytic layer, can have any suitablethickness, such as about 10 nm to about 200 nm, about 20 nm to about 200nm, about 20 nm to about 100 nm, about 40 nm to about 60 nm, about 50 nmto about 55 nm, or any thickness in a range bounded by, or between, anyof these values.

In some embodiments, the photocatalytic material comprises tin. Forexample the photocatalytic material could be an oxide of tin, such asSnO₂.

In some embodiments, the non-photocatalytic material comprises copper.For example, the non-photocatalytic material could be copper metal.

The photocatalytic layer and the non-photocatalytic material may haveany suitable volume ratio. In some embodiments, the photocatalytic layerand the non-photocatalytic material may have a volume ratio (volumecatalytic layer/volume non-catalytic material) that is about 1 to about100, about 1 to about 50, about 3 to about 50, about 3 to about 20,about 5 to about 10, about 6 to about 8, or any ratio in a range boundedby, or between, any of these values.

In some embodiments where a non-photocatalytic source material or metalis co-sputtered or intimately mixed with a photocatalyst material, thenon-photocatalytic source material or metal comprises more than about 5molar % of the resulting thin layer. In some embodiments, thenon-photocatalytic source material or metal comprises more than about 10molar %, more than about 20 molar %, more than about 30 molar %, morethan about 40 molar %, more than about 50 molar %, more than about 60molar %, or more than about 70 molar %.

A co-catalyst includes a material that enhances the photocatalyticproperties of a photocatalyst. Co-catalysts may also be genericallyreferred to as T-binder throughout this document. In some embodiments, aco-catalyst may improve catalytic performance. For example a co-catalystmay increase a rate of catalysis by at least about 1.2, at least about1.5, at least about 1.8, at least about 2, at least about 3, or at leastabout 5. One method of quantifying the rate of catalysis may includedetermining a rate of decomposition of an organic compound, such asacetaldehyde. For example, if the concentration of acetaldehyde werephotocatalytically decreased to 80% of its original value after 1 hour,or by 20%, an increase in the rate of catalysis of about 2 would resultin the amount of acetaldehyde being decreased to 60% of its originalvalue after 1 hour, or by 40%. A rate of catalysis may be measured as adecrease in a compound such as acetaldehyde due to composition, at agiven time point, such as about 0.5 hours, 1 hour, 1.5 hours, 2 hours,2.5 hours, 3 hours, or 5 hours after the photocatalysis is initiated.

Some co-catalysts may be compounds or semiconductors that are capable ofbeing reduced by electron transfer from the conduction band of thephotocatalyst. For example, a co-catalyst may have a conduction bandhaving a lower energy than the conduction band of the photocatalyst, ora co-catalyst may have a lowest unoccupied molecular orbital having alower energy than the conduction band of the photocatalyst. When a termsuch as “lower energy” and “higher energy” is used to compare a band ofa semiconductor or a molecular orbital with another band or molecularorbital, it means that an electron loses energy when it is transferredto the band or molecular orbital of lower energy, and an electron gainsenergy when it is transferred to the band or molecular orbital of higherenergy.

It is believed that some metal oxides that are co-catalysts are capableof reducing O₂. For example, it is believed that CeO₂ can reduce O₂ gasby electron transfer. In doing so, it is believed that Ce³⁺ transfers anelectron to O₂ and is converted to Ce⁴⁺ as a result. In a photocatalystcomposition, a photocatalyst may transfer an electron to CeO₂, thusconverting Ce⁴⁺ to Ce³⁺, and the Ce³⁺ may then reduce O₂. Ce³⁺ may alsobe present as a result of equilibrium processes involving CeO₂ and O₂,and superoxide radical ion (O₂ ⁻). O₂ and superoxide radical ion in suchan equilibrium process may be adsorbed to the surface of solid CeO₂ orpresent in the atmosphere. Ce³⁺ may also be present as a result ofoxidation and reduction reactions with cerium species of differentoxidation states that may be added intentionally or present asimpurities.

Some co-catalysts may be capable of converting atmospheric O₂ tosuperoxide radical ion. For example, CeO₂ is capable of convertingatmospheric oxygen to superoxide radical ion. It is believed that someof the equilibrium and/or electron transfer processes described abovemay contribute to this property of CeO₂. Such a conversion may occurunder a variety of conditions, such as ambient conditions, including forexample, normal atmospheric oxygen concentrations, such as molarconcentrations of about 10% to about 30%, about 15% to about 25%, orabout 20% oxygen; ambient temperature, such as about 0° C. to about1000° C., about 0° C. to about 100° C., about 10° C. to about 50° C., orabout 20° C. to about 30° C.; and pressure, such as about 0.5 to about 2atm, about 0.8 atm to about 1.2 atm, or about 1 atm. Such a conversionmay also occur under elevated or reduced temperature, pressure, oroxygen concentration. Other materials that may be capable of reducing O₂or converting atmospheric O₂ to superoxide radical ion include variousother materials such as Ce_(x)Zr_(y)O₂ (where x:y=0.99-0.01),BaYMn₂O_(5+δ), and lanthanide-doped CeO₂ including Ce_(x)Zr_(y)La_(z)O₂,Ce_(x)Zr_(y)Pr_(z)O₂, and Ce_(x)Sm_(y)O₂.

Some co-catalysts may have a valence band or a highest occupiedmolecular orbital at a higher energy than a valence band of thephotocatalyst. This may allow a hole in a valence band of thephotocatalyst to be transferred to a highest occupied molecular orbitalor a valence band of the co-catalyst. The hole in the valence band orhighest occupied molecular orbital of co-catalyst may then oxidize H₂Oor OH⁻ to OH⁻. For example, if WO₃ is chosen as a photocatalyst,examples of suitable co-catalysts include anatase TiO₂, SrTiO₃, KTaO₃,SiC, or KNbO₃.

In some embodiments, the co-catalyst is inorganic. In some embodiments,the inorganic co-catalyst is a binder. In some embodiments, theco-catalyst is an oxide, such as a metal dioxide, including CeO₂, TiO₂,or the like.

In some embodiments, the co-catalyst comprises CuO, MoO₃, Mn₂O₃, Y₂O₃,Gd₂O₃, TiO₂, SrTiO₃, KTaO₃, SiC, KNbO₃, SiO₂, SnO₂, Al₂O₃, ZrO₂, Fe₂O₃,Fe₃O₄, NiO, Nb₂O₅, In₂O₅, Ta₂O₅, or CeO₂. In some embodiments, theco-catalyst comprises In₂O₅, Ta₂O₅, anatase TiO₂, rutile TiO₂, acombination of anatase and rutile TiO₂, or CeO₂.

In some embodiments, the co-catalyst can be Re_(r)E_(t)O_(s), wherein inRe is a rare earth element, E is an element or a combination ofelements, and O is oxygen, and 1≤r≤2, 2≤s≤3, and 0≤t≤3. In someembodiments, the co-catalyst can be Re_(r)O_(s) where Re can be a rareearth metal and r can be greater than or equal to 1 and less than orequal to 2, or can be between 1 and 2 and s can be greater than or equalto 2 and less than or equal to 3 or can be between 2 and 3. Examples ofsuitable rare earth elements include scandium, yttrium and thelanthanide and actinide series elements. Lanthanide elements includeelements with atomic numbers 57 through 71. Actinide elements includeelements with atomic numbers 89 through 103. In some embodiments, theco-catalyst can be Ce_(x)Zr_(y)O₂ wherein the y/x ratio=0.001 to 0.999.In some embodiments, the co-catalyst can be cerium. In some embodiments,the co-catalyst can be CeO_(a) (a≤2). In some embodiments, theco-catalyst can be cerium oxide (CeO₂).

In some embodiments, the co-catalyst is CeO₂ doped with Sn, such asabout 1 molar % to about 50 molar %, about 5 molar % to about 15 molar%, or about molar 10% Sn, based upon the total number of moles ofco-catalyst.

In some embodiments, the photocatalyst is WO₃ and the co-catalyst isCeO_(a) (a≤2).

In some embodiments, the co-catalyst is a Keggin unit, e.g., ammoniumphosphomolybdate ((NH₄)₃[PMo₁₂O₄₀]), 12-phosphotungstic acid,silicotungstic acid, or phosphomolybdic acid. The overall stability ofthe Keggin unit allows the metals in the anion to be readily reduced.Depending on the solvent, acidity of the solution and the charge on theα-Keggin anion, it can be reversibly reduced in one- or multipleelectron step.

In some embodiments, the photocatalytic layer is formed of the materialsdescribed herein.

While not wanting to be limited by any particular theory, the inventorsbelieve that CeO₂ may be useful in conjunction with tungsten oxidebecause of the relative band positions of these materials. Furthermore,it is noted that the index of refraction of CeO₂ is substantially thesame as tungsten oxide, about 90% to about 110% compared to tungstenoxide. In some embodiments, the index of refraction is about 95% toabout 105% compared to tungsten oxide. In some embodiments, the hightransparency of the photocatalytic compositions provides acomposition/layer/element of transparency greater than about 50%, 60%,65%, and/or 70%. The low scattering losses due to matched refractiveindices contributes directly to a transparent composition.

Any useful ratio of photocatalyst to co-catalyst may be used. In someembodiments, a photocatalytic composition has a molar ratio(photocatalyst:co-catalyst) of about 1:5 to about 5:1, about 1:3 toabout 3:1, about 1:2 to about 2:1, or about 1:1.

In some embodiments, a composition comprises tungsten oxide and a rareearth oxide at a molar ratio of about 0.5:1 to 2:1 or about 1:1(tungsten oxide:rare earth oxide). In some embodiments, the rare earthoxide is cerium oxide (CeO₂). In some embodiments, the photocatalyticcomposition includes WO₃ and CeO₂, having a molar ratio (WO₃:CeO₂) ofabout 1:5 to about 5:1, about 1:3 to about 3:1, about 1:2 to about 2:1,or about 1:1.

FIG. 1 is a schematic representation of the structure of someembodiments according to the present disclosure. A transparentphotocatalytic composition 100 is formed of a photocatalyst material 102and a co-catalyst 104. Light waves 106 are emitted from a source 108external to transparent photocatalytic composition 100 in a directionthrough it. In some embodiments, a photocatalytic element is provided,the element comprising transparent photocatalytic composition 100. Insome embodiments, the element is a layer. In some embodiments, theelement is a coating disposed over a substrate,

In some embodiments, source 108 may comprise a photoluminescent material(phosphorescent or fluorescent), an incandescent material, an electro-or chemo- or sono- or mechano- or thermo-luminescent material. Suitablephosphorescent materials include ZnS and aluminum silicate whereasfluorescent materials include phosphors like YAG-Ce, Y₂O₃—Eu, variousorganic dyes etc. Incandescent materials include carbon, tungsten whileelectroluminescent materials include ZnS, InP, GaN, etc. It will beevident to one of ordinary skill in the art that any other kind of lightgeneration mechanism would suffice for providing the energy to initiatephotocatalysis, e.g., sunlight, fluorescent lamp, incandescent lamp,light-emitting diode (LED) based lighting, sodium vapor lamp, halogenlamp, mercury vapor lamp, noble gas discharges, and flames.

FIG. 2 is a schematic representation of a system 200, which ischaracteristic of some embodiments disclosed herein. In someembodiments, a transparent photocatalytic element 202 is providedincluding a substrate 204 and transparent photocatalytic composition100, the composition including at least one photocatalyst material 102and co-catalyst 104 contacting at least a portion of substrate 204. Insome embodiments, transparent photocatalytic composition 100 is appliedto or disposed upon substrate 204, at least a portion of transparentphotocatalytic composition 100 contacting surface 206 of substrate 204or a portion thereof. In some embodiments, photocatalyst material 102and co-catalyst 104 have refractive indices within about 0.75, about0.50, about 0.20, or about 0.05 of each other. For example, in someembodiments, where the photocatalyst material 102 is WO₃ and co-catalyst104 is CeO₂, the respective refractive indices are 2.20 and 2.36.

In some embodiments, the photocatalytic composition is coated to asubstrate in such a way that the photocatalyst composition comes intocontact with light and material to be decomposed.

By being disposed upon the substrate, the photocatalytic composition isa separately formed layer, formed prior to disposition upon thesubstrate. In some embodiments, photocatalytic composition 100 is formedupon the substrate surface, e.g., by sputtering; vapor deposition likeeither chemical vapor deposition (CVD) or physical vapor deposition(PVD); laminating, pressing, rolling, soaking, melting, gluing, spincoating; dip coating; bar coating; slot coating; brush coating;sputtering; thermal spraying including flame spray, plasma spray (DC orRF); high velocity oxy-fuel spray (HVOF) atomic layer deposition (ALD);cold spraying or aerosol deposition. In some embodiments, thephotocatalytic composition is incorporated into the surface of thesubstrate, e.g., at least partially embedded within the surface.

Suitable deposition rates according to the present disclosure includerates between about 1 nm/min and about 100 nm/min, about 10 nm/min andabout 50 nm/min, about 15 nm/min and about 30 nm/min, or about 20nm/min.

Suitable deposition times according to the present disclosure includefrom about 1 minute to about 120 minutes, from about 1 minute to about60 minutes, or from about 10 minutes to about 40 minutes.

Suitable thicknesses achieved according to the present disclosure ofsome or all of the layers that may be deposited depending on thespecific embodiment in question may be between about 1 nm to about 100nm, between about 5 nm and about 50 nm, or between about 10 nm and about30 nm.

In some embodiments, the photocatalyst composition substantially coversthe substrate 204. In some embodiments, the photocatalyst compositioncontacts or covers at least about 75%, at least about 85%, or at leastabout 95% of substrate surface 206.

A larger surface area may translate into higher photocatalytic activity.In some embodiments, the Brunner Emmett Teller BET specific surface areaof the photocatalyst is between about 0.1 m²/g and about 500 m²/g. Insome embodiments, the BET specific surface area of the photocatalyst isbetween about 10 m²/g and about 50 m²/g.

In some embodiments, a photocatalytic layer is provided including theaforementioned compositions of tungsten oxide to rare earth oxide.

Some embodiments comprise a method for making a photocatalyticcomposition including creating a dispersion comprising a CeO₂photocatalyst and a dispersing media, wherein the respectivephotocatalyst and CeO₂ refractive indices are within at least 0.75 ofeach other, the molar ratio of the photocatalyst to CeO₂ being betweenabout 1-99 molar % photocatalyst and about 99-1 molar % CeO₂; whereinthe dispersion includes about 2-50 wt % solid materials; applying thedispersion to a substrate; and heating the dispersion and the substrateat a sufficient temperature and length of time to evaporatesubstantially all the dispersing media from the dispersion. In someembodiments, the dispersion is applied to cover the substrate, either inwhole or in part, or is applied to a surface of the substrate to createa coating or surface layer.

FIG. 3 is a schematic view showing a sputtering apparatus employed fordepositing the transparent composition 100 on a surface or substrate.That is, while being connected with a cathode 303, a target 302 made ofthe photocatalytic material 102, such as SnO₂, Sn metal, WO₃, or Wmetal; or a metal, such as Cu, or co-catalyst 104, such as CeO₂, to besputtered onto the substrate 204, is installed in the inside of a vacuumchamber 301. On the other hand, a substrate 204 to deposit thetransparent composition 100 thereon can be installed on an anode 305side.

At the time of film formation, chamber 301 is initially evacuated to bein a vacuum state by a vacuum gas discharge pump 306. In someembodiments, the term “vacuum state” refers to a low pressure of lessthan about 10 pascals, less than about 5 pascals, less than about 2pascals, less than about 1 pascal, less than about 0.5 pascals, or lessthan about 0.4 pascals. In some embodiments, the term “vacuum state”refers to a low pressure of less than about 1×10⁻² torr, less than about2×10⁻³ torr, and even less than about 1×10⁻³ torr. After achieving avacuum state, discharge gases, e.g., argon (Ar) and/or oxygen (O₂), areintroduced from a gas supply source 307. An electric field is appliedbetween the anode 305 and the cathode 303 from an electric power source310 to start plasma discharge 308. Subsequently, the surface of thetarget 302 is sputtered and the metal tungsten and oxygen are bonded onthe substrate 204 to form a photocatalytic element 202. In this case,the electric power to be loaded from the electric power source 110 maybe DC (direct current) power or RF (radio frequency) power.

In embodiments where RF power is used, the RF power is between about 100W and about 1000 W, between about 300 W and about 700 W, or about 500 W.

In embodiments where DC power is used, the DC power is between about 0.1kW and about 10 kW, between about 0.5 kW and about 5 kW, about 0.5 kW,or about 1 kW.

In some embodiments, a method of manufacturing an anti-bacterial coatedarticle comprises forming a thin layer of any of the photocatalyticcompositions described in the previously filed application Ser. No.13/738,243, filed Jan. 10, 2013, e.g., embodiments of claims 1-47, on asubstrate by sputtering at least one photocatalytic source and at leastone metal and/or co-catalytic source as target material in an atmosphereof a sputtering gas.

In some embodiments, the photocatalytic source is at least one tungstensource. In some embodiments, the at least one tungsten source is WO₃and/or W metal. In some embodiments, the photocatalytic source is atleast one tin (Sn) source. In some embodiments, the at least one tinsource is SnO₂ and/or Sn metal.

In some embodiments, the at least one co-catalyst source is any of theco-catalytic materials described elsewhere in this application. In someembodiments, the co-catalyst source is CeO₂.

In some embodiments, the at least one metal source is any of the metalmaterials described elsewhere in this application. In some embodiments,the metal source is Cu, CuO, and/or Cu₂O. In some embodiments,sputtering of the metal materials is performed under a substantiallypure inert gas atmosphere. In some embodiments, the sputtering of themetal materials is performed under a mixture of an inert gas and oxygen.While not wanting to be limited by any particular theory, it is believedthat varying the amount of O₂ gas in the metal sputtering atmosphere canallow for oxidizing the metal materials sputtered/created upon thetarget surface.

In some embodiments, the sputtering gas atmosphere is an inert gas.While not wishing to be limited by any particular theory, it is believedthat the atomic weight of the sputtering gas should be close to theatomic weight of the target material. In some embodiments, thesputtering gas is helium, argon, krypton, xenon, nitrogen, and/oroxygen. In some embodiments, the sputtering gas is argon. In someembodiments, the sputtering gas atmosphere further comprises a reactivegas. Reactive sputtering involves reacting a gas with the targetmaterial as it travels between the substrate and the target. In someembodiments, when the targeting source does not provide sufficientprecursor elements to assemble the desired end-product, e.g., when theat least one tungsten source is W metal, the sputtering gas atmospherefurther comprises a reactive gas. In some embodiments, the reactive gasis an oxide, a nitride and/or a sulfide. In some embodiments, thereactive gas is an oxide or oxygen source, e.g., O₂ gas. In someembodiments, the sputtering gas atmosphere comprising O₂ gas is betweenabout 1% to about 100% O₂ and the argon gas is between about 99% toabout 0%. In some embodiments, the sputtering gas is provided at a gaspressure of at least about 10 standard cubic centimeters per minute(sccm). In some embodiments, the sputtering gas (or each sputtering gasif a mixture of sputtering gases is used) is provided at about 1, about2, about 4, about 8, about 10, about 20, about 80 sccm, about 90 sccm,and/or about 100 sccm

As shown in FIGS. 4 and 5, a photocatalytic element of some embodimentscomprises a first layer 502 comprising a photocatalytic material, e.g.,tungsten, and a second layer 504 comprising co-catalyst, e.g., CeO₂. Insome embodiments, the layer 502 comprising a photocatalytic compositionis separate from layer 504 comprising the co-catalyst. In someembodiments, the thin layer comprises a first layer formed from the atleast one tungsten source and a second layer formed from the at leastone co-catalyst source.

As shown in FIG. 2, transparent composition 100 according to someembodiments comprises a co-sputtered layer. The co-sputtered layercomprises both co-catalyst 104 and photocatalytic material 102. In someembodiments, co-catalyst 104, e.g., CeO₂, and photocatalytic material102, e.g., a tungsten material, is co-sputtered onto substrate 204. Insome embodiments, the co-sputtered layer comprises an increasing ordecreasing concentration gradient of the co-sputtered materials.

As shown in FIG. 4, a second layer 504 of some embodiments comprisingthe co-catalyst, e.g., CeO₂, is disposed, contacted with and/orsputtered onto a surface 606 of a substrate 604. In some embodiments,the first layer 502 comprising the photocatalytic material, e.g.,tungsten, is disposed upon and/or atop, contacted with and/or sputteredonto a surface 507 of a second layer 504. In some embodiments, secondlayer 504 is disposed between and/or interposed between first layer 502and substrate 604.

As shown in FIG. 5, the first layer 502 of some embodiments comprisingthe photocatalytic material, e.g., comprising tungsten, can be disposed,contacted with and/or sputtered onto a surface 606 of the substrate 604.In some embodiments, the second layer 504 comprising the co-catalyst isdisposed upon and/or atop, contacted with and/or sputtered onto surface608 of first layer 502. In some embodiments, first layer 502 is disposedbetween and/or interposed between second layer 504 and substrate 604.

As shown in FIG. 6, first layer 502 of some embodiments comprising thephotocatalytic material, e.g., comprising tin and/or tin oxide, isdisposed, contacted with and/or sputtered onto surface 606 of substrate604. In some embodiments, second layer 504 comprising the metal, e.g.,copper, is disposed upon and/or atop, contacted with and/or sputteredonto surface 608 of first layer 502. In some embodiments, first layer502 is disposed between and/or interposed between second layer 504 andsubstrate 604. In some embodiments, second layer 504 is a discontinuouslayer defining apertures or voids between islands of material, e.g., Cu.

As it will be described later, in such a sputtering apparatus, aphotocatalytic film with a predetermined film quality can be obtained byadjusting the electric power loaded for plasma discharge, the pressureand the composition of the ambient gas at the time of sputtering, and/orthe temperature of the substrate.

In some embodiments, the temperature of the substrate can be betweenabout room temperature (T_(r)) and about 800° C. In some embodiments,the substrate temperature can be between about 100° C. and about 500° C.In some embodiments, the substrate temperature can be, for example,about 250° C. and/or about 400° C.

In some embodiments, the sputtering is by the application of directcurrent (DC) to the sputtering apparatus. In some embodiments, thedirect current applied to drive the sputtering is between about 100 V toabout 500 V In some embodiments, the sputtering is performed by varyingthe sign between the electrodes at about 13.56 MHz (RF)

Some embodiments comprise a method for making a photocatalyticcomposition including mixing an aqueous dispersion of a visible lightphotocatalyst and CeO₂, the ratio of the photocatalyst to CeO₂ beingbetween about 40-60 molar % photocatalyst and about 60-40 molar % CeO₂;adding sufficient dispersing media, e.g., water, to attain a dispersionof about 10-30 wt % solid materials; applying the dispersion to asubstrate; and heating the substrate at a sufficient temperature andlength of time to evaporate substantially all the water from thedispersion and the substrate. In some embodiments, the CeO₂ is a sol. Insome embodiments, the photocatalyst material is added to the CeO₂ sol.In some embodiments, the CeO₂ is added to a photocatalyst dispersion. Insome embodiments, both the photocatalyst dispersion and CeO₂ sol ordispersion are prepared separately and then mixed together to create thedispersion.

In some embodiments, the ratio of the photocatalyst to CeO₂ may be about2:3 to about 3:2, such as between about 40-60 molar % photocatalyst andabout 60-40 molar % CeO₂. In some embodiments, the ratio ofphotocatalyst to CeO₂ is about 1:1 [50 molar % to 50 molar %]. In someembodiments, the CeO₂ is a sol.

In some embodiments, the amount of dispersing media, e.g. water, addedis sufficient to attain a dispersion of about 2-50 wt %, about 10-30 wt%, or about 15-25 wt % solid materials. In some embodiments, the amountof dispersing media, e.g., water, added is sufficient to attain adispersion of about 20 wt % solid materials

In some embodiments, the dispersion-covered substrate is heated at asufficient temperature and/or sufficient length of time to substantiallyremove the dispersing media. In some embodiments at least about 90%, atleast about 95%, at least about 99% of the dispersing media is removed.In some embodiments, the dispersion-covered substrate is heated at atemperature between about room temperature and about 500° C., betweenabout 100° C. and about 400° C., or about 400° C. In some embodiments,the dispersion covered substrate is heated to a temperature betweenabout 90° C. and about 150° C. In some embodiments, the dispersioncovered substrate is heated to a temperature of about 120° C. In someembodiments, the substrate is heated by being irradiated by a lamp, suchas a Xe lamp, where the power of the lamp may be between about 100 W andabout 500 W, between about 200 W and about 400 W, or about 300 W.

While not wanting to be limited by any particular theory, it is believedthat keeping the temperature below 500° C. may reduce the possibility ofthermal deactivation of the photocatalytic material, for example due tophotocatalytic material phase change to a less active phase(highly-active anatase TiO₂ to less active rutile), dopant diffusion,dopant inactivation, loaded material decomposition or coagulation(reduction in total active surface area).

In some embodiments, the dispersion-covered substrate is heated for atime between about 10 seconds and about 2 hours. In some embodiments,the dispersion-covered substrate is heated for a time of about 1 hour.

The dispersions described herein can be applied to virtually anysubstrate. Other methods of applying the dispersion to a substrate caninclude slot/dip/spin coating, brushing, rolling, soaking, melting,gluing, or spraying the dispersion on a substrate. A proper propellantcan be used to spray a dispersion onto a substrate.

In some embodiments, the substrate need not be capable of transmittinglight. For example, the substrate may be a common industrial orhousehold surface on which a dispersion can be directly applied. Suchsubstrates can include, glass (e.g., windows), walls (e.g., drywall),stone (e.g., granite counter tops), masonry (e.g., brick walls), metals(e.g. stainless steel), woods, plastics, other polymeric surfaces,ceramics, and the like. Dispersions in such embodiments can beformulated as paints, liquid adhesives on tape, coatings on wallpapers,drapes, lamp shades, light covers, tables, counter tops, and the like.

A photocatalyst composition may be capable of photocatalyticallydecomposing an organic compound, such as an aldehyde, includingacetaldehyde formaldehyde, propionaldehyde, etc.; a hydrocarbon, such asan alkane, including methane, ethane, propane, butane, etc.; an aromatichydrocarbon, such as benzene, naphthalene, anthracene, etc.; crude oil,or fraction thereof; dyes such as anthocyanins, methylene blue, basicblue 41; volatile organic compounds, such as methane, ethane, propane,butane, benzene, toluene, acetone, diethyl ether, methanol, ethanol,isopropyl alcohol, formaldehyde, ethyl acetate, xylene, etc.; NO_(x),such as NO, NO₂, N₂O, HONO; SO_(N), such as SO₂, SO₃, etc.; CO, O₃;etc., small organic molecules such as caffeine, diclofenac, ibuprofen,geosmin, flumequine, etc., bacteria such as Escherichia coli,Staphylococcus aureus, Acinetobactor, Pseudomonas aeruginosa etc., virussuch as MS2, influenza, norovirus, etc., bacterial spores such asClostridium difficile, protozoa such as Giardia, etc., and fungi such asCandida, etc. Photocatalytic decomposition may occur in a solid, liquid,or a gas phase.

To test the photocatalytic ability of a photocatalyst composition,gas-phase decomposition of acetaldehyde may be used. A photocatalystsample is dispersed in water or other solvent including methanol orethanol. A binder may be added to this dispersion in such a way as toproduce a final dispersion with about 10-50% solid content. Thedispersed sample can be homogenized using an ultrasonic probe. Thedispersion can then be applied to a substrate. The substrate-applieddispersion combination can then be heated to about 120° C., therebyevaporating substantially all of the dispersant. Thereafter it can besubjected to high intensity UV illumination for about one hour forproducing a pristine photocatalyst surface.

This photocatalyst composition/substrate can be placed in a Tedlar Bag(5 L) which can then be filled with about 3 L air from a compressed airsource. Thereafter, acetaldehyde from a calibration-grade source can beadded to achieve a final acetaldehyde concentration of about 80 ppm asmeasured using a calibrated gas chromatograph equipped with a highsensitivity flame ionization detector (GC-FID).

This gas bag sample can be equilibrated in the dark for about an hourand gas chromatography and flame ionization detection (GC-FID) can beused to confirm a stable concentration of acetaldehyde. A monochromaticblue light-emitting diode array (455 nm) with 200 mW/cm² intensity ofillumination at the exposure plane can be then used to irradiate thebag. Gas samples can be collected from the bag using an automated systemand analyzed using the GC-FID. Temporal variation of the concentrationof acetaldehyde can be determined from the area under the correspondingpeak of the chromatogram. Other suitable gas detection scheme likeGastec gas detection tubes may also be used for determining theacetaldehyde concentration in the bag.

The gas decomposition rate (%) can be set as a value calculated based onformula [(X−Y)/X·100], where X represents a gas concentration beforelight irradiation and Y represents a gas concentration when the gasconcentrations are measured.

In some embodiments, the acetaldehyde decomposition rate provided by thedesired level of photocatalytic activity is at least about 10% in about1 hour with above-mentioned illumination. In some embodiments, thedecomposition rate is at least about 30% in about 1 hour. In someembodiments, the rate is 50% in about 1 hour. In some embodiments, thedecomposition rate is at least about 80% in about 1 hour.

In some embodiments, a photocatalyst material contains the photocatalystpowder according to the embodiment whose content falls within a range ofnot less than 0.1 molar % nor more than 99 molar %. In some embodiments,a photocatalyst coating material contains the photocatalyst materialaccording to the embodiment whose content falls within a range of notless than about 1 molar % nor more than about 90 molar %.

The photocatalyst material, compositions, and dispersions describedherein can be used as a disinfectant, an odor eliminator, a pollutanteliminator, a self-cleaner, an antimicrobial agent and the like. Thematerials, compositions, and dispersions can be used to interact withair, liquid, microbial and/or solid substances. In some embodiments,they can be used to clean air such as in confined environments such asin aircraft fuselages or in more contaminated environments such as autogarages. In other embodiments, they can be used for antimicrobialproperties such as to coat surfaces in need of disinfection such as foodservice or production facilities or hospitals or clinics.

In some embodiments, methods are utilized wherein polluted air isexposed to light and a photocatalyst material, composition, ordispersion as described herein thereby removing pollutants from the air.

In some embodiments, light and a photocatalyst material, composition, ordispersion can remove about 50%, about 60%, about 70%, about 80%, about90%, about 95% or more of the pollution in the air.

In some embodiments, methods are utilized wherein polluted water isexposed to light and a photocatalyst material, composition, ordispersion as described herein thereby reducing the amount ofcontaminant in the water.

In some embodiments, light and a photocatalyst material, composition, ordispersion can remove about 50%, about 60%, about 70%, about 80%, about90%, about 95% or more of the pollution from the water.

In some embodiments, methods are utilized wherein biologicalcontaminants are exposed to light and a photocatalyst material,composition, or dispersion as described herein thereby disinfecting thebiological material. In some embodiments, biological materials includefood products.

In some embodiments, light and a photocatalyst material, composition, ordispersion can remove about 50%, about 60%, about 70%, about 80%, about90%, about 95% or more of the contamination from the biological materialin the air.

SAMPLE PREPARATION

All materials were used without further purification unless otherwiseindicated.

Example 1A Manufacturing the Photocatalvtic Element (Ex-1)

A tungsten metal disc (about 5 mm thick and about 6 inches in diameter)was provided as a tungsten source material and placed on a targetplatform (cathode side) within a vacuum chamber of a ULVAC SH-450sputtering apparatus. A 10 mm×10 mm square of Quartz and Silicon waferwas placed on the anode side. After sealing the chamber, the vacuum wasdropped to about 1×10⁻³ Pa. The sputtering apparatus was provided withthe following parameters: driving voltage about 500 W (RF), Ar gas (80sccm), and O₂ gas (at about 20 sccm) were introduced into the vacuumchamber (maintained at about 4 pascals [Pa]) to achieve a depositionrate of about 20 nm/min. After completion of sputtering, the sputteredsubstrate was removed and annealed in an oven for about 60 minutes atabout 400° C.

Example 1A-2

A substrate was sputtered in a manner similar to that described inExample 1A, except that the sputtering parameters were changed, e.g., Argas (4 sccm) and O₂ gas (at about 4 sccm) were introduced into thevacuum chamber (maintained at about 1 Pa).

Example 1B Manufacturing the Photocatalvtic Element (Ex-2)

A tungsten metal disc was provided as a source material and placed onthe target platform (cathode side) within the vacuum chamber of a ULVACSH-450 sputtering apparatus. A 10 mm×10 mm square of Quartz and Siliconwafer was placed on the anode side. After sealing the chamber, thevacuum was dropped to about 1×10⁻³ Pa. The sputtering apparatus wasprovided with the following parameters: driving voltage (DC) about 1 kW,Ar gas 20 sccm, and O₂ gas 20 sccm were introduced. Vacuum chamberpressure was maintained at about 2 Pa to achieve a deposition rate ofabout 20 nm/min. After completion of sputtering, the sputtered substratewas removed and annealed in an oven for about 60 minutes at about 400°C.

Example 1B-2

A substrate was sputtered in a manner similar to that described inExample 1B, except that the sputtering parameters were changed, e.g., Argas (80 sccm) and O₂ gas (at about 20 sccm) were introduced into thevacuum chamber (maintained at about 4 Pa) to encourage crystallization.

Example 1C

A mixture of WO₃ and CeO₂ (50 molar % of each) was provided as a sourcematerial and placed on the target platform (cathode side) within thevacuum chamber of a ULVAC SH-450 sputtering apparatus. A 10 mm×10 mmsquare of ITO coated glass was placed on the anode side. After sealingthe chamber, the vacuum was dropped to about 1×10⁻³ Pa. The sputteringapparatus was provided with the following parameters: driving RF powerabout 500 W, Ar gas 90 sccm, and O₂ gas 10 sccm were introduced. Vacuumchamber pressure was maintained at about 0.2 Pa. After completion ofsputtering, the sputtered substrate was removed and annealed in an ovenfor about 60 minutes at about 400° C.

Example 1D

A 10 mm×10 mm square of Quartz was placed on the anode side within thevacuum chamber of a ULVAC SH-450 sputtering apparatus. Tin oxide (SnO₂)and copper (Cu) metal discs were provided as source material and placed,spaced apart from each other, on the target platform (cathode side).After sealing the chamber, the vacuum was dropped to about 1×10⁻³ Pa.The respective SnO₂ and Cu discs were positioned relative the shutteringaperture/shuttering aperture closed so as not to be in a sputteringposition, e.g., disposed opposite an opening communicating the anode andthe cathode. The sputtering apparatus was provided with the followingparameters for pre-sputtering or cleaning the target platform:drivingvoltage (DC) about 0.5 kW, Ar gas 20 sccm, and O₂ gas 20 sccm wereintroduced. Vacuum chamber pressure was maintained at about 0.34 Pa forabout 10 min.

After the pre-sputtering, the shutter was opened/positioned so that theSnO₂ target disc was opposite the opening communicating the anode andcathode, and the sputtering apparatus was provided with the followingparameters: driving voltage (RF) about 500 W, Ar gas 20 sccm, and O₂ gas20 sccm were introduced. Vacuum chamber pressure was maintained at about2 Pa to achieve a deposition rate of about 20 nm/min. SnO₂ depositiontime was about 60 mins.

After SnO₂ sputtering and 10 min of pre-sputtering as described above(shutter closed/cathode isolated from anode), the shutter of the ULVACSH-450 sputtering apparatus was positioned/opened so that the copper(Cu) metal disc/cathode was opposite the opening communicating betweenthe anode and cathode. The SnO₂ sputtered 10 mm×10 mm square of Quartzand Silicon wafer was left on the anode side after completion of SnO₂sputtering. The vacuum was stabilized at about 0.34 Pa. The sputteringapparatus was provided with the following parameters: driving voltage(DC) about 100 W, and Ar gas 20 sccm was introduced. Vacuum chamberpressure was maintained at about 0.46 Pa Cu deposition time was about 2min. After completion of sputtering, the sputtered substrate was removedand annealed in an oven for about 60 minutes at about 400° C. Therespective sputtered layer thicknesses of about 52 nm (SnO₂) and about 7nm (Cu) were measured by using a scanning probe microscope (SPM)(HitachiNano Navi II/E-Sweep, Hitachi High-Tech Science Corporation, Japan). Thedeposed Cu appeared as a very thin layer or island structure (not fullycovering the SnO₂ layer)

Comparative Example 1E

A sputtered quartz sample was prepared in a manner similar to Example 1Dabove, except that no SnO₂ sputtering was performed upon the quartzsample prior to Cu sputtering as described in Example 1D above. Thesputtered layer thicknesses of about 7 nm (Cu) was measured by using ascanning probe microscope (SPM)(Hitachi Nano Navi II/E-Sweep, HitachiHigh-Tech Science Corporation, Japan). The Cu appeared as a very thinlayer or island structure (not fully covering the quartz substratelayer.

Example 4

A sputtered glass slide prepared in a manner similar to Examples 1D and1E above, except that glass slides are substituted for the substrateplaced on the anode side, is heated at about 120° C. on a hot plateunder full spectrum irradiation by a Xe lamp (lamp power output about300 W) for about 1 hour. Each slide is then sealed in a separate 5 LTedlar bag under vacuum, followed by injecting about 3 L of ambient airand about 80 mL of 3500 ppm acetaldehyde. Each bag is then lightlymassaged for about 2 minutes by hand then placed in the dark for about15 min. The acetaldehyde concentration is then estimated by GasChromotagraphy-Flame Ionization Detector (GC-FID) to be at 80±2 ppm.Each Tedlar bag containing a sample is placed back in the dark for about1 hour. The slide/Tedlar bag is then exposed to array blue LED of 455 nmwith light intensity of 50 mW/cm². A sample is collected every 30minutes by an automated injection port of GC-FID and the amount ofremaining acetaldehyde estimated at subsequent 30 minute intervals. Itis anticipated that when a T-binder co-catalyst is combined with WO₃,performance will be at least comparable to bare WO₃.

Examples 5-7

5 g of WO₃ (Global Tungsten & Powder, Towanda, Pa., USA [GTP]) was addedto high purity alumina ball mill jars containing about 50 g of ZrO₂balls of about 3 mm in diameter and was ground by ball mill (SFM-1 modelDesktop Planetary Ball Miller (MTI Corp. location) in 25 mL methanol forabout 4 hours to obtain ground WO₃ (GTP) with a smaller particle size.Plasma-WO₃ was made in a manner similar to that described in U.S. Pat.No. 8,003,563, which is hereby incorporated by reference in itsentirety.

Additional glass slides were made and placed in a Tedlar bag in asimilar manner to that described in Example 4, except that 200 mg eachof WO₃ (GTP) (Example 5 w/, Example 5a w/out), Ground WO₃ (GTP) (Example6 w/, Example 6a w/out) and plasma-WO₃ (Example 7 w/, Example 7a w/out)each with and without CeO₂ were spin-coated on glass substrate insteadof LPD-WO₃.

The spin-coated slides WO₃, Ground WO₃, find and plasma-WO₃ each withand without CeO₂ were prepared and were tested for acetylaldehydedegradation.

Example 8: Combination of Combustion Ti(O,C,N)₂:Sn and Plasma CeO₂Towards Acetaldehyde Degradation

In another example, Ti(O,C,N)₂:Sn was combined with plasma CeO₂ powder(1:1 mole ratio) in a similar manner to that described in a previousexample, except that Ti(O,C,N)₂:Sn powder was used instead of WO₃powder, and was spin coated on a glass micro slide as described inExample 1. The Ti(O,C,N)₂:Sn was synthesized as described in co-pendingU.S. Patent Provisional Application Ser. No. 61/608,754, filed Mar. 8,2012, which is hereby incorporated by reference in its entirety, by anaqueous combustion method employing glycine (1.4 g) as a completelydecomposable fuel in addition to titanium (IV) bis ammonium lactatedihydroxide (7 mL of 50 wt % aqueous solution), tin octoate (0.883 g)and ammonium nitrate (3.5 g) at 300° C. followed by annealing at 400° C.for 30 min in the box furnace. A glass slide made in a manner similar tothat of the previous examples was tested for acetaldehyde degradation asalso earlier described (at 270 mW/cm² light intensity). 7% Acetaldehydedegradation was observed for the Ti(O,C,N)₂:Sn photocatalyst coatedglass slide in a Tedlar bag. When, a glass slide with both Ti(O,C,N)₂:Snand CeO₂ (1:1 mole ratio) was tested in a Tedlar bag, the acetaldehydedegradation increased to 22%.

Example 9 Photocatalvtic Inactivation of E. coli (ATCC 8739)

A substrate (1″×2″ glass slide) was prepared by sequential applicationof 70% IPA (Isopropyl Alcohol), 100% EtOH and then dried in air. Ex-1Dand Comparative Example 1-E were sputtered as described in the Examplesabove to attain about 1 mg of the material on the substrate. The coatedsubstrates were then placed in a glass dish with a water soaked filterpaper for maintaining moisture. Glass spacers were inserted between thesubstrates and the filter paper to separate the substrates from thefilter paper.

E. coli (ATCC 8739) was streaked onto a 5 cm diameter petri dishcontaining about 25 ml of LB agar, and was incubated at about 37° C.overnight. For each experiment, a single colony was picked to inoculateabout 3 mL nutrient broth, and the inoculated culture was incubated atabout 37° C. for about 16 hours to create an overnight culture (˜10⁹cells/mL). A fresh log-phase culture of the overnight culture wasobtained by diluting the overnight culture×100, inoculating another 5 cmpetri dish with LB agar and then incubated at about 37° C. for about 2.5hr. The fresh culture was diluted 50×, which gave a cell suspension ofabout 2×10⁶ cells/mL. 50 uL of the cell suspension was pipetted ontoeach glass substrate. A sterilized (in 70% and then 100% EtOH) plasticfilm (20 mm×40 mm) was placed over the suspension to spread thesuspension evenly under the film. At chosen time point, e.g., about 30minute increments, the specimen was placed in 10 mL of 0.85% saline andvortexed at 3200 rpm for about 1 min to wash off the bacteria. The washoff suspension was serially diluted using 0.85% saline, and plated on LBagar and incubated at about 37° C. overnight to determine the number ofviable cells in terms of CFU/Specimen. Counting was performed by visualinspection and the result multiplied by the dilution factor to arrive atthe determined number. The specimen was then irradiated and positionedunder a 1000 Lx fluorescent lamp. The results are shown in FIG. 7,wherein the Cu-only sputtered sample showed less than 10⁻² reduction,sputtered Cu/SnO₂ showed about the same activity in dark, and sputteredCu/SnO₂ sample showed at least 10⁻² (about 4.3×10⁻⁴ reduction) morereduction than either the Comparative Example 1-E or Example 1-D in thedark.

Example 38 Reducing Odor on an Airliner

A dispersion including a photocatalyst composition as described hereinis provided as a coating on a thin adhesive film. This adhesive film isused to coat the ceiling of a Boeing 737. The photocatalyst compositioncan react with ambient light from light emitting diode light fixturesabove the overhead bins to generate reactive airborne species that canreduce odor in the air.

Example 39: Disinfecting Food Preparation Surfaces

A photocatalyst resin capable of being applied as a spray is provided toa food preparation factory to coat its work surfaces. The resin can beapplied in a heated or unheated state in order to properly bond with awork surface. All surfaces that are to come into contact with food inthe factory are sprayed with the resin.

The factory is equipped with organic light emitting diode light fixturesfor general lighting. This ambient light can react with the resinsurface thereby creating oxygen radicals on the surface. These radicalscan react with food contaminants thereby rendering the food safe. As aresult of applying the resin to the work surfaces, instances of bacteriaspreading into the food supply has reduced 50%.

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as molecular weight, reaction conditions,and so forth used in the specification and claims are to be understoodas being modified in all instances by the term “about.” Accordingly,unless indicated to the contrary, the numerical parameters set forth inthe specification and attached claims are approximations that may varydepending upon the desired properties sought to be obtained. At the veryleast, and not as an attempt to limit the application of the doctrine ofequivalents to the scope of the claims, each numerical parameter shouldat least be construed in light of the number of reported significantdigits and by applying ordinary rounding techniques.

The terms “a,” “an,” “the” and similar referents used in the context ofdescribing the invention (especially in the context of the followingclaims) are to be construed to cover both the singular and the plural,unless otherwise indicated herein or clearly contradicted by context.All methods described herein can be performed in any suitable orderunless otherwise indicated herein or otherwise clearly contradicted bycontext. The use of any and all examples, or exemplary language (e.g.,“such as”) provided herein is intended merely to better illuminate theinvention and does not pose a limitation on the scope of any claim. Nolanguage in the specification should be construed as indicating anynon-claimed element essential to the practice of the invention.

Groupings of alternative elements or embodiments disclosed herein arenot to be construed as limitations. Each group member may be referred toand claimed individually or in any combination with other members of thegroup or other elements found herein. It is anticipated that one or moremembers of a group may be included in, or deleted from, a group forreasons of convenience and/or patentability. When any such inclusion ordeletion occurs, the specification is deemed to contain the group asmodified thus fulfilling the written description of all Markush groupsused in the appended claims.

Certain embodiments are described herein, including the best mode knownto the inventors for carrying out the invention. Of course, variationson these described embodiments will become apparent to those of ordinaryskill in the art upon reading the foregoing description. The inventorexpects skilled artisans to employ such variations as appropriate, andthe inventors intend for the invention to be practiced otherwise thanspecifically described herein. Accordingly, the claims include allmodifications and equivalents of the subject matter recited in theclaims as permitted by applicable law. Moreover, any combination of theabove-described elements in all possible variations thereof iscontemplated unless otherwise indicated herein or otherwise clearlycontradicted by context.

In closing, it is to be understood that the embodiments disclosed hereinare illustrative of the principles of the claims. Other modificationsthat may be employed are within the scope of the claims. Thus, by way ofexample, but not of limitation, alternative embodiments may be utilizedin accordance with the teachings herein. Accordingly, the claims are notlimited to embodiments precisely as shown and described.

What is claimed is:
 1. A photocatalytic material comprising aphotocatalytic layer comprising tin, and a non-photocatalytic materialcomprising copper, wherein part of the non-photocatalytic material is indirect contact with the photocatalytic layer, and wherein thephotocatalytic layer and the non-photocatalytic material have a volumeratio that is about 3 to about
 50. 2. The photocatalytic material ofclaim 1, wherein the photocatalytic layer comprises SnO₂.
 3. Thephotocatalytic material of claim 1, wherein the non-photocatalyticmaterial comprises copper metal.